1. Technical Field
This invention relates to a multiplexer.
2. Description of the Related Art
With advancement in wireless communication technology, various wireless communication services can be used in mobile digital terminals. Such various wireless communication services include a Global System for Mobile communication (GSM) using a frequency band of 890 to 960 MHz, Personal Communication Services (PCS) using a frequency band of 1.8 GHz, World Interoperability for Microwave Access (WiMAX) using a frequency band of 3.6 to 3.8 GHz, a Wireless Local Area Network (WLAN) using a frequency band of 2.4 GHz or 5 GHz, Wireless Broadband Internet (WiBro) using a frequency band of 2.3 GHz, Bluetooth using a frequency band of 2.4 GHz, etc.
Recently, a multi-band antenna system has been used in mobile digital terminals to use wireless communication services provided at various frequency bands. The multi-band antenna system requires a resonator capable of achieving both narrow band characteristics and improved blocking characteristics.